Hep B is transmitted, as you said, by risky behaviors. And it is also commonly transmitted to health care personnel who have contact with those who engage in risky behaviors. I'll grant you that it may not turn out to be good policy to vaccinate young teens and preteens for Hep B. Could well be. There are not any significant side effects evident yet, so the trade-off looks promising. But you suggested that this is profit-driven, and it is not. (What babies do you see getting the vaccine?!) The philospohy behind this is to reduce the "chronic carriers" in order to reduce the incidence of infection for all of us. Younger people are more likely to be the newly infected.
BTW, our children may be very well brought up, but even well-brought-up young people can go through wilder stages and be influenced by riskier behaviors. Hep B is not presently curable. It destroys livers and often makes chronic invalids of people.
But this was not a scheme designed to make a lot of money. Companies are not generally eager to mfg vaccines because they are cheap and given to such a wide population. Over a large enough population, this means there will inevitably be bad results, or bad outcomes that can't even be linked to vaccines, and the companies find themselves blamed.
I'm grateful that some company saw fit to finally get the tetanus vaccine back into availability. All you have to do is get a bite from an animal...